Power transfer element with automatically acting device for the adjustment of length for maintaining a predetermined clearance, especially for readjustment of the ventilating play in the case of brakes

ABSTRACT

Power transmitting element having an automatically acting device for adjustment of length for stabilization of a predetermined idle path with an adjusting element movable axially in one direction and stopped in the other axial direction by a backstop, for adjustment of play in brakes.

United States Patent Totschnig I 1451 Aug. 29, 1972 Manfred KarlTotschnig, Wolfsburg, Germany Inventor:

Assignee: Volkswagenwerk Aktiengesellschaft,

Wolfsburg, Germany Filed: Aug. 20, 1970 Appl. No.2 65,365

Foreign Application Priority Data Sept. 3, 1969 Germany ..P 19 44 586. 4

US (:1. ..188/196 1) 1m, (:1 ..F16d 65/56 Field of Search..188/71.8,71.9, 79.5 GE, 196 D References Cited UNITED STATES PATENTS 2,949,1738/1960 Peras ..l88/71.9 X 3 ,244,260 4/1966 Frayer 1 88/7 I .9 X

FOREIGN PATENTS OR APPLICATIONS 1,294,718 4/1962 France ..188/71 .9

Primary ExaminerDuane A. Reger Attorney-Watson, Cole, Grindle & WatsonABSTRACT Power transmitting element having an automatically actingdevice for adjustment of length for stabilization of a predeterminedidle path with an adjusting element movable axially in one direction andstopped in the other axial direction by a backstop, for adjustment ofplay in brakes.

8Claims,lDrawingFigure P'A'IENTEDwazs m2 3.681.243

IN V EN TOR.

Mafia-ed K, 73Z'se m 4 aZo This invention relates to a power transferelement with an automatically acting device for adjustment of length forstabilization of a predetermined idle path with an adjusting elementmovable in relation to a main part axially in one direction and stoppedin the other axial direction by means of a backstop, especially forreadjustment of the ventilating play in the case of brakes.

In the case of a known arrangement of this type, the journal, Lusinenouvelle, No. 29 of July 16, 1959, the force acting in one direction istransferred to the slanting surfaces of two wedge elements by means oftwo cylindrical rollers touching along a generatrix. Said rollers as aresult thereof, are pressed with their outside surfaces against aparallel construction and, by their friction with the parallelconstruction, they prevent a change in length of the power transmissionelement. In the case of a power effect in the opposite direction, thefriction brake becomes ineffective by means of a spring system so thatnow the desired change in length can be accomplished.

In the case of this known power transmitting element and subject to theflat wedge angles, great forces in a transverse direction develop. Inorder to be able to absorb these forces large cross sections of theloaded elements are needed which in turn require great weight. The greatforces result in high surface pressures which require a hardening of thewedge surfaces. The sensitivity to tolerance, likewise conditional onthe flat wedge angles, requires a very precise fabrication.

The installation of a constant length into the power transmissionelement, in which a change of length in both directions is possible, itcannot be carried out because as a matter of principle the deviceoperates without an idle path. In the case of brakes which have beenequipped with such a power transmitting element, the influence of theventilating play must be taken into account elsewhere.

For reasons of strength it is likewise not possible to construct theknown arrangement so small that it can also be used in smaller brakes.

This invention is based on the object of constructing a powertransmission element which adapts itself better to the particularpurpose of its use, particularly as a readjusting device. It is expectedto save space and weight without any limitation of its effectivefunctioning and safety in operation and, with regard to production, itis supposed to be particularly suitable for mass production.

According to the invention, this will be achieved by the adjustingelement being axially freely movable by the amount of the idle path and,as compared to the main element, and that a collet and male screwengaging with the collet with a thread without automatic locking serveas a device for the adjustment in length whereby a part of said devicefor the adjustment of length is rotatable and shiftable axially by meansof a stop in one end position upon exceeding the idle path and inrelation to the other part, and by a rotational safety device assignedto the rotatable element and effective in the other end position, afterreturn movement of the adjusting element by the idle path.

Advantageously, the thread of the collet and the male screw is developedas a trapezoidal thread because the latter is well suited on the onehand as a thread of movement and on the other hand, from the point ofview of fabrication, it can be produced without difficulty.

In a further development of the invention, a friction brake serves as asafety device against rotation which softly absorbs the torque that isto be transferred in a locking direction. At the same time one will beable to achieve with it in a simple manner, a continuous adjustment inlength.

In order to achieve an increased braking effect or else to build in morespace saving which is to say, the same thing, the friction brake may bedeveloped as a cone brake.

Further objects of the invention will be apparent from the followingdescription when considered in connection with the accompanying drawingsin which;

The FIGURE is a part longitudinal section and part side view of thepower transmitting element developed as a pressing rod.

Referring to the FIGURE of the drawing, the pressing rod consistsessentially of a main element 1 l, the adjusting element 12 in the formof a threaded sleeve, the male screw 13 and the tightening pin 14. Thethread in elements 12 and 13 is a trapezoidal thread with a steep pitchlying outside the automatic locking. The male screw 13 at its right handend together with the main element 11 has been formed as a cone brake15.

In the case of a longitudinal movement of the main element 11 and of theadjusting element 12 in the direction a, free wheeling direction, themale screw 13 is pressed against the stop 14 after the idle path orspace L has been exceeded. In the case of a further effect of thetraction force, the male screw begins to turn, since the friction momentalong the point of contact between the tightening pin 14 and thesphere-shaped front side 16 of the male screw is smaller than the torqueproduced by the male screw and thus makes possible a further extensionin length of the power transmitting element.

An axial movement in both directions is possible by the amount of theidle path L. The maximum readjusting path N as well as idle path L areconstructionally conditional and to a large extent are freelyselectable.

In the case of an axial movement of the main element 11 and theadjusting element 12 in direction b," locking effect, the front side 16is freed of the stop 14. Main element and adjusting element can now bepushed together by or to the extent of the idle path L, since the conebrake 15 becomes then effective. The angle of pitch of the trapezoidalthread must be selected in dependence on the angle of the cone, suchthat the braking moment will be greater than the torque produced by themale screw. The reaction moment is absorbed by the tightening pin 14 orby the places of attachment 1'7 and 18.

It will be possible by means of a return peg or pin 19, which is pushedinto the bore of the main element 11 provided for this purpose, insteadof the locking plug 110 and which acts on the likewise ball-shaped frontsurface 111 of the male screw constructed in regard to measurements insuch a way that the cone brake becomes ineffective at the same time tomove the parts 11 and 12 toward each other also in direction b,possibility of readjustment.

The recesses 112, 113 and 114 are grease grooves in order to achieveimproved sliding properties of the threaded sleeve 12 in the mainelement 11.

Numerals 115 and 116 designate gaskets under prestress which besidestheir actual sealing objective, will simultaneously prevent the malescrew from tuming under the influence of oscillations.

The plug 110 and the protective cup 117 will prevent the penetration ofdirt inside the pressing rod.

1 claim:

1. Power transfer element with automatically acting length equalizingdevice for maintaining a predetermined clearance constant, with anadjusting element movable relative to a main part axially in onedirection and restrainable by means of a return lock in the other axialdirection, especially for the readjustment of the ventilation clearancein the case of rakes, wherein the adjusting element is freely movableaxially by the clearance dimension relative to the main part, andwherein a thread casing and a threaded spindle, having reversiblethreaded engagement therein, serve as the length equalizing device, andwherein the threaded spindle is rotatable and in one terminal position,after having exceeded the clearance, is axially shiftable relative tothe thread casing by means of a stop, and wherein a rotational safetyelement effective in the other terminal position, after return movementof the adjusting element, has been adjoined to the threaded spindle,characterized in that a peg which can be introduced in the area of therotational safety element through an opening in the main part makes therotational safety element ineffective, so that it is possible for theadjusting element to be returned without relative rotation of the mainpart and the thread casing.

2. Power transfer element according to claim 1, characterized in thatthe main part is constituted by a casing in which the adjusting elementconsisting of the thread casing and the threaded spindle is mounted, andwherein means are provided to prevent relative rotation of casing andthread casing.

3. Power transfer element according to claim 2, characterized in thatthe last means serves also as a stop for the threaded spindle.

4. Power transfer element according to claim 3, characterized in thatthe end of the threaded spindle facing the stop is spherical.

5. Power transfer element according to claim 1, characterized in thatthe terminal area of the threaded spindle facing away from the stop anddeveloped as a cone rake serves together with the main part as therotational safety element.

6. Power transfer element according to claim 1, characterized in thatthe end of the threaded spindle facing away from the stop is spherical.

7. Power transfer element according to claim 1, characterized in thatbetween the threaded spindle and the thread casing on the one hand andbetween the threaded spindle and the main part on the other hand,

additional means have been provided to prevent an undeslred readustment, for example, as a result of shocks during driving.

8. Power transfer element according to claim 7, characterized in thatthe additional means consist of sealing rings.

1. Power transfer element with automatically acting length equalizingdevice for maintaining a predetermined clearance constant, with anadjusting element movable relative to a main part axially in onedirection and restrainable by means of a return lock in the other axialdirection, especially for the readjustment of the ventilation clearancein the case of rakes, wherein the adjusting element is freely movableaxially by the clearance dimension relative to the main part, andwherein a thread casing and a threaded spindle, having reversiblethreaded engagement therein, serve as the length equalizing device, andwherein the threaded spindle is rotatable and in one terminal position,after having exceeded the clearance, is axially shiftable relative tothe thread casing by means of a stop, and wherein a rotational safetyelement effective in the other terminal position, after return movementof the adjusting element, has been adjoined to the threaded spindle,characterized in that a peg which can be introduced in the area of therotational safety element through an opening in the main part makes therotational safety element ineffective, so that it is possible for theadjusting element to be returned without relative rotation of the mainpart and the thread casing.
 2. Power transfer element according to claim1, characterized in that the main part is constituted by a casing inwhich the adjusting element consisting of the thread casing and thethreaded spindle is mounted, and wherein means are provided to preventrelative rotation of casing and thread casing.
 3. Power transfer elementaccording to claim 2, characterized in that the last means serves alsoas a stop for the threaded spindle.
 4. Power transfer element accordingto claim 3, characterized in that the end of the threaded spindle facingthe stop is spherical.
 5. Power transfer element according to claim 1,characterized in that the terminal area of the threaded spindle facingaway from the stop and developed as a cone rake serves together with themain part as the rotational safety element.
 6. Power transfer elementaccording to claim 1, characterized in that the end of the threadedspindle facing away from the stop is spherical.
 7. Power transferelement according to claim 1, characterized in that between the threadedspindle and the thread casing on the one hand and between the threadedspindle and the main part on the other hand, additional means have beenprovided to prevent an undesired readjustment, for example, as a resultof shocks during driving.
 8. Power transfer element according to claim7, characterized in that the additional means consist of sealing rings.